<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style type="text/css">
        .main {
            width: 250px;
            height: 50px;
            display: flex;
        }
        .div1 {
            background: #03A9F4;
            flex-grow: 1;
            flex-shrink: 1;
            flex-basis: 0;
        }
        .div2 {
            background: aquamarine;
            flex-grow: 1;
            flex-shrink: 1;
            flex-basis: 0
        }
    </style>
</head>
<body>
<div class="main">
    <div class="div1">11</div>
    <div class="div2">1111111111</div>
</div>
</body>
</html>